I think you can make a good case, on the basis of climbing times, that the peloton is cleaner (not necessarily clean). I don’t see what relevance that has to the competitiveness of the Tour. If a bunch of riders clean are close to one another in their performance levels, are huge gaps going to open up as a result of doping? Only if some of them have much better programs than others, and Floyd’s/Tyler’s testimony doesn’t particularly support that. Maybe LA, that remains to be seen, but what about, e.g., Basso? In 2006 he was the dominant climber in the world, now he is only one of the better ones. Is this because he had a better program in 2006 than anyone else? A program that allowed him to perform much better than, say, Cunego and Evans? Is the theory that they were always clean, and now that Basso is, too, he is no better than they are?
Maybe, but then what about Floyd? We know he doped, yet even doped he would not have come close to winning the TDF in 2006 if Basso had been there. With Basso, Ulle, and Vino out, the 2006 TDF was actually quite competitive, but we know it wasn't particularly clean.
What about Bert? Anyone really think he would have won the TDF in 2007 if Basso had not been suspended and was riding that Tour? Then how has it happened that he is now, even after the Giro and crashes, out-performing Ivan? Is the theory that Ivan back then had a doping edge over a clean Bert, and now they are both clean? Really?
The point is that a lot of factors go into making the differences in performances between one rider in different years and different riders in the same year. You can’t look at this Tour, the relatively even performances, and make any conclusions about doping. It's quite possible to have a Tour like this with riders doped to the gills, and conversely, it's possible to have a clean race where one rider dominates.
I also disagree with the contention that when riders are doping, they ride like robots, that don’t even get tired. The point of doping is to improve the performance you’re capable of when going all out, not to achieve the same or slightly better performance while taking it a little easier. Someone who has raised his crit and goes all out will feel every bit as exhausted as someone with a natural HT who goes all out.
Power measurements, meaning climbing times, SRM data, and the like, are the best indicators of what the riders are or are not putting into their bodies right now. How exciting/competitive/exhausting the Tour becomes is another question entirely, one I would say is quite unrelated to the cleanliness of the peloton.